At the end of Baldur's Gate II: Throne Of Bhaal, Jaheira's reaction if you're in a relationship with her and decide to remain mortal. If you don't, well...that's another trope entirely.
No one likes Anomen at first, but once you make him into a paladin or whatever, he gets much, much better, where he even apologizes to Keldorn for being such a dick. Anyway the bit where he gives my a character a camelia rose always touches me...d'awwww.
Aerie's dialogue in the same situation. She's been traumatised in the past by the loss of her wings, and a good part of the romance arc is about showing her that life is worth living even after that loss, and she does have the strength to go on. When offered godhood, you point out that with the power of a god, you could restore her wings. Her response? 'Forget my wings; I would rather have you'.
Aerie's romance ending takes the cake. After giving birth to two kids, she and Player Character travels to her home land and finds her parents who never gave up their search for her, and she and Player Character finally married there.
If you play a girl, and can't romance her, instead you just get gushing most of the time you speak to her. She really does think the world of you.
What makes it better is that Aerie thought her mother dies after confronting the wraith in ToB. Then, in the epilogue, it's revealed that not only she is still alive and well (and her father as well), she never gave up searching that her daughter.
After advancing Jaheira's plotline enough, rest in the wild and bandits will attack you and hold her hostage. Depending on your choices, you get a very touching scene in which Jaheira goes Tsundere and promises you she will not allow it. She will not lose a loved one again. Never again...
Minsc's epilogue has him finally returning home, happy he helped the Bhaalspawn but convinced he'll be seen as a failure due to the death of his witch, Dynaheirnote Killed by Irenicus, the Elminster-level mage, at the beginning of BG2... only to find himself being hailed as a champion for all his heroic exploits, causing him to start up his own adventuring company and continue, natch, "buttkicking for goodness" well into old age.
Korgan is an evil dick, but still his comment about not harming children are sincere and come pretty much out of left field.
When you're about to fight Irenicus at Suldanessellar, you'll give your companions the options to leave if they wish. They'll decline the offer. Viconia takes the cake, especially if you're good. She'll stand by your side because you've been nice to her.
If you are in a romance with Viconia, right at the very end of Throne of Bhaal, shortly before you leave for the final battle, she tells you that she loves you. You may have to persuade her to change her alignment to neutral to do so, which is another case of this in and of itself.
It is possible to persuade Sarevok to become good.
Cernd picks up that CHARNAME is a Bhaalspawn but concludes you are still your own person and it doesn't have to get in the way of your friendship.
Speaking of friendship, Dorn is pretty vocal about how much he doesn't trust others and considers his fellow teammates allies of conveniance at best. He even has a lengthy dialogue in the first game where he lists reasons you can't trust or rely on your comrades. So what happens when you see his questline through to its conclusion in Throne of Bhaal? He calls you "friend". That's right, after all the hatred, prejudice and betrayal in his life, he feels like he's finally found someone he can trust and appreciate.
While Jarlaxle is a Manipulative Bastard towards you, he clearly cares about his men. He refuses to send them on a suicide mission against the guardian lich, he'd rather let you do it. When you accuse The Dragon for lying to you, Jarlaxle question him and when he concludes that he didn't lie, his reaction is "though as such" and later when The Dragon does slip on another subject, Jarlaxle casually forgives him. Jarlaxle may be a drow and a Manipulative Bastard, but he's a Father to His Men.
There are quite a number of heartwarming moments of banter between the squadmates. To wit:
Keldorn talks to Aerie about serving Torm. Aerie comments that she often feels like a mangled pastiche, being an avariel who worships Baervan Wildwanderer, a gnomish god. Keldorn remarks that Aerie might actually be considered a pure example of faith, devoting herself to the church, and not just a god whose goals she aligns with.
It's oddly touching to see Dorn and Korgan bond over their shared love of killing and destruction.
Mazzy grew up with stories of Keldorn, and the two can meet. They have nothing but praise for each other's skill.
Now an archmage, Nalia asks Keldorn if he thinks his battles mean anything, as she constantly sees evil in the world, and little changes. Keldorn tells her she is young and therefore impatient, and change will come, if people like her don't give up.
Korgan may be an Ax-Crazy psychopath, but he agrees to try and be civil in human lands for Mazzy's sake.
Mazzy tells Aerie not to be afraid to dream about having wings, because one never knows when the gods could be listening.
Cernd is claustrophic, and Mazzy offers to help him through it.
Mazzy remarks to Nalia that she knows Nalia blames herself for the death of her father, as she wasn't strong enough to stop the trolls in time. She helps her get past it.
Nalia takes a dour turn in Throne of Bhaal, and Jan tells her an outlandish story to make her laugh. He admits that he missed her smile.
If he changed alignment in Throne of Bhaal Sarevok tells Nalia that she is repulsed by him because she sees many of his qualities in her: Power, leadership, and initiative. He tells her to be cautious, for there were many people who started out like her, and ended up like him.
Likewise, in a conversation with Imoen if you chose to Have her give a piece of her soul to revive him she starts to ask how it feels. After a bit of mocking and later scaring her recounting what she went through..if you did the alignment change he tells her he can feel many things and knows she is stronger than she thinks she is. Imoen is positively speechless and taken aback.
Yoshimo tells Nalia about an intricate trap he had to disarm once, and Nalia remarks that she worries immensely if someone gets hurt by a trap because she could not disarm it. He tells her that she is skilled, and will not disappoint.
Viconia remarks that Imoen should be more subservient to CHARNAME since s/he saved Imoen's life many times. Imoen reverses the question on Viconia and asks if she would do the same. If romanced, Viconia admits she loves CHARNAME; if not, she still says she supports CHARNAME.
Despite not really liking each other, Viconia remarks that Jaheira's talents and attitude would bring her great respect among her people. She might not live to see it, but they would respect her.
If Aerie heads down into the Underdark, she's predictably afraid of going in. If Minsc is in the party (and has adopted her as his new witch) he'll assure her that everything's going to be all right and that he'll protect her.